Missile impact resistant exterior sheathing building panel

ABSTRACT

An impact resistant exterior sheathing gypsum building panel with an integrated impact resistant woven mesh which protects against impact from projectiles such as those conveyed by hurricane force winds is provided. Methods for manufacturing these exterior sheathing gypsum building panels with an integrated impact resistant woven mesh are also provided. An exterior sheathing system employing the exterior sheathing cementitious building panel is provided.

FIELD OF THE INVENTION

This invention relates to a hurricane resistant gypsum exteriorsheathing building panel and methods for manufacturing and installingthe panel. The product would be used on the exterior of a building toprovide impact resistance in high impact applications such as hurricaneresistant housing requiring significant mechanical strength at or alongthe outer surface of the exterior sheathing building panel to preventfailure due to projectile impact.

BACKGROUND OF THE INVENTION

In states such as Florida where geographic location subjects buildingsand homes to high winds, perhaps of hurricane force, building standardsrequire walls and building panels to withstand certain impacts, such asimpact of an eight foot long two inch by four inch wooden stud weighingabout 9 pounds (4.1 kg) which impacts endwise on the panel face at 34miles per hour (about 50 feet per second, 15.2 m/s). After such impact,the impacted area resists at least one-third the vacuum pressure thepanel resisted before impact, starting at a pre-impact minimum of about90 pounds per square foot.

There is a need for missile impact resistant gypsum panel, for examplein hurricane zones to meet such standards. Current practices to meethigh velocity hurricane zone (HVHZ) large scale missile impactresistance require field installation involving additional labor stepsand field applied materials such as field applied impact resistantmeshes.

Currently impact resistant meshes are all field applied materials.Current system installations involve fastening GMS (glass mat sheathing)substrate panels to traditional framing members in a variety of spacingschedules depending on the architect's design requirements.Additionally, subsequent layering of basecoat, impact resistant mesh,foam, basecoat, surface crack resistant mesh and finish layer(s) (suchas stucco) are installed as EIFS (energy insulation finishing system)components. Typically the impact mesh component used is critical tomeeting the high velocity hurricane zone large missile impact resistancerequirements. This is an additional step above and beyond normal EIFSsystem requirements. This incurs material and labor costs along withscheduling restraints in the installations.

There remains a desire for new missile impact damage resistant gypsumpanel articles which are easy to install for use in high wind areassubject to prone to hurricane force winds, as well as methods ofpreparing such articles.

BRIEF SUMMARY OF THE INVENTION

The invention relates to an improved gypsum exterior sheathing buildingpanel which would provide large scale missile impact resistance asrequired in high velocity hurricane zones (HVHZ), coastal areas. Theproposed panel would be a product pre-assembled at the factory toinclude elements required to meet HVHZ performance standards. This wouldsimplify installation in the field thereby reducing delivered systemcosts and time to install by contractors. In the present specificationthe term pre-fabricated means the panel is made to have the elementsrequired to meet HVHZ performance standards, for example an embeddedimpact resistant mesh layer, at a manufacturing facility before deliveryto a building site.

The building panel of the invention would include an embedded impactresistant woven mesh in the gypsum core. This would eliminate the needto field apply a comparable mesh and basecoat to attain the requiredsystem performance.

In one aspect, the present disclosure is directed to a building panel,suitable as an exterior sheathing gypsum building panel, which providelarge scale missile impact resistance as required in high velocityhurricane zones (HVHZ), coastal areas.

In particular, the invention provides an exterior sheathing buildingpanel comprising from front to back:

-   -   a first fibrous mat,    -   a gypsum core layer having front and rear surfaces, the gypsum        core layer having a thickness of 0.5 to 1.25, preferably 0.5 to        1, inches, wherein the first fibrous mat is attached as a facer        cover sheet to the front surface of the gypsum core layer,    -   an impact resistant woven scrim mesh, embedded ¼ to 1/16 inch,        preferably ⅛ to 1/16 inch, from the rear surface of the gypsum        core layer,    -   a second fibrous mat attached as a backer cover sheet to the        rear surface of the gypsum core layer,    -   wherein the gypsum core layer comprises at least 75 wt. %        calcium sulfate material, wherein the gypsum core layer        comprises less than 10 wt. % magnesium oxide, preferably less        than 5 wt. % magnesium oxide, most preferably an absence of        magnesium oxide;    -   wherein the first fibrous mat and second fibrous mat        respectively comprise paper or fibrous material of at least one        of polymer fibers, glass fibers, mineral fibers or a combination        thereof,    -   wherein the impact resistant mesh has an Impact Range        Classification of >150 in-pounds (>17.0 J) (also known as        “Ultra-High”) according to ASTM E2486 (2018) Standard Test        Method for Impact Resistance of Class PB and PI Exterior        Insulation and Finish Systems (EIFS).

The rear mat is always partially embedded to bond the back facer to thepanel core. The mesh is always spaced from the rear mat to form a gapfilled with slurry to bond the mat to core bond. Typically the gap isabout 1/16 inch-⅛ inch embedment. The slurry penetration into the matranges from 40 to 60% of the mat thickness.

Typically the above-described impact resistant mesh has one or more ofthe following properties:

fabric surface weight of 20 to 30 ounces per square yard (690 to 1035g/m²) (measured according to ASTM D3776/D3776M-09a (2017), Standard TestMethods for Mass Per Unit Area (Weight) of Fabric, ASTM International,West Conshohocken, Pa., 2017),

a thickness of 0.040 to 0.045 inches (1.02 to 1.14 mm)(measuredaccording to ASTM D-1777-96 (2015), Standard Test Method for Thicknessof Textile Materials, ASTM International, West Conshohocken, Pa., 2015),and

a minimum tensile strength of 350 to 540 pounds-force per inch (2.41 to3.72 MPa) in the warp and weft, respectively (measured according to ASTMD-5035-11 (2019), Standard Test Method for Breaking Force and Elongationof Textile Fabrics (Strip Method), ASTM International, WestConshohocken, Pa., 2019).

In particular, the exterior sheathing building panel of the inventionmeets 2017 Florida Building Code Test—Protocols for High-VelocityHurricane Zone, Chapter 16, Section 1626, Sixth Edition, to be capableof resisting a 2 inches×4 inches (51 mm×102 mm) missile weighing 9pounds (4.1 kg) in accordance with 2017 Florida Building CodeTest—Testing Application Standard (TAS) 201-94 Impact Test Procedures.Per Section 1626.2.4, the missile shall impact the surface of each testspecimen at a speed of 50 feet per second (34 miles per hour; 15.2 m/s).Typically this missile is a 2 inch×4 inch×8 foot wood stud.

Thus, generally the exterior sheathing building panels of the inventionare capable of preventing panel penetration by an eight foot long twoinch by four inch missile (projectile such as a 2 inch×4 inch×8 footwood stud) weighing about 9 pounds (4.1 kg) and impacting the panel faceendwise at 34 miles per hour.

After such impact, the impacted area resists at least one-third thevacuum pressure the panel resisted before impact, starting at apre-impact minimum of about 90 pounds per square foot.

2017 Florida Building Code Test—Protocols for High-Velocity HurricaneZone, Chapter 16, Section 1626, Sixth Edition establishes the 2017Florida Building Code definition of the missile and the impactresistance requirement for building components requiring large missileimpact resistance in jurisdictions designated a high velocity hurricanezone (HVHZ). Florida Building Code Test Protocols for High-VelocityHurricane Zones, Chapter 16, Section 1626, Sixth Edition, 2017 is astricter standard than, for example, that set forth in ASTMInternational's Standard Classification for Abuse-Resistant NondecoratedInterior Gypsum Panel Products and Fiber-Reinforced Cement Panels (ASTMC1629) which applies to panels for use in high traffic areas (e.g., suchas dormitories, hospitals, etc.).

2017 Florida Building Code Test—Testing Application Standard (TAS)201-94 Impact Test Procedures covers procedures for conducting theimpact testing of materials as required by the Test—Protocols forHigh-Velocity Hurricane Zone, Chapter 16, Section 1626, Sixth Edition.2017 Florida Building Code Test—Testing Application Standard (TAS)201-94 Impact Test Procedures test procedures provide a means ofdetermining whether a particular product used as wall cladding, exteriorwindows, glazing, exterior doors, skylights, glass block, shutters andany other similar devise used as external protection to maintain theenvelope of the building, provides sufficient resistance to wind-bornedebris.

In another aspect, the invention provides methods of preparing gypsumexterior sheathing building panels of the invention described in thepresent disclosure. The method of making the building panel, comprises:

-   -   depositing a first fibrous mat as a face mat on a surface,    -   mixing at least water and calcium sulfate material to prepare an        aqueous gypsum slurry comprising at least 75 wt. % calcium        sulfate material on a dry (water free) basis, wherein said        calcium sulfite material comprises calcium sulfate hemihydrate,    -   wherein the aqueous gypsum slurry comprises less than 10 wt. %        magnesium oxide on a dry (water free) basis, preferably less        than 5 wt. % magnesium oxide on a dry (water free) basis, most        preferably an absence of magnesium oxide;    -   applying the aqueous gypsum slurry in a bonding relation to the        face mat to form a gypsum core layer, the gypsum core layer        having a face side and a back side, wherein the gypsum core        layer face side faces said face mat;

applying an impact resistant woven scrim mesh on the back side of thegypsum core layer to embed the impact resistant woven scrim mesh intothe gypsum core layer,

-   -   wherein the impact resistant mesh has an Impact Range        Classification of >150 in-pounds (>17.0 J) (also known as        “Ultra-High”) according to ASTM E2486 (2018) Standard Test        Method for Impact Resistance of Class PB and PI Exterior        Insulation and Finish Systems (EIFS);    -   applying a second fibrous mat as a back mat on the back side of        the gypsum core layer having the embedded impact resistant mesh        to form a board precursor, thereby locating the aqueous slurry        between the face mat and the back mat;    -   allowing the aqueous gypsum slurry located between the face mat        and the back mat to set, thereby forming the gypsum exterior        sheathing building panel.

The gypsum core of the gypsum panel comprises set gypsum, namely calciumsulfate dihydrate resulting from setting the aqueous gypsum slurrycomprising calcium sulfate hemihydrate and optionally calcium sulfateanhydrite. Typically when the calcium sulfate material and water aremixed the resulting aqueous gypsum slurry has at least 75 wt. %,preferably at least 85 wt. %, most preferably at least 95 wt. %, on adry basis calcium sulfate hemihydrate. In other words, the aqueousgypsum slurry is at least 75 wt. %, preferably at least 85 wt. %, mostpreferably at least 95 wt. %, on a dry basis calcium sulfate hemihydrateprior to setting.

In another aspect, the present disclosure is directed to an exteriorsheathing system comprising framing to which is attached at least oneexterior sheathing building panel of the invention which prevents waterpenetration and air leakage. In particular, the invention provides anexterior sheathing building panel of the invention as described in thepresent disclosure, wherein the impact resistant mesh faces towards theframing. The exterior sheathing building panel of the invention would beused on the exterior of a building, typically an exterior wall, toprovide an impact resistant barrier. The framing is of wood, metal orany other building framing material. The exterior sheathing buildingpanels are attached to the framing by screws, nails, glue, or otherbuilding fasteners. Preferably the exterior sheathing building panel hasno perforations except for perforations made by the screws or nails.

For purposes of this specification the terms “board” and “panel” areinterchangeable.

These and other advantages of the present invention, as well asadditional inventive features, will be apparent from the description ofthe invention provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a first example of a gypsum exteriorsheathing building panel of the present invention with an impactresistant woven scrim mesh embedded in its gypsum core.

FIG. 2 shows a side cross sectional view of the gypsum exteriorsheathing building panel of FIG. 1 with the impact resistant woven scrimmesh embedded in its gypsum core.

FIG. 3 shows a perspective view of the exterior sheathing building panelof the present invention attached to one side of a metal stud wallsuitable in the exterior wall system of the present invention.

FIG. 4 shows a photograph of a front view of Test Sample 1 Impact 1 ofthe examples.

FIG. 5 shows a photograph of a rear view of Test Sample 1 Impact 1 ofthe examples.

FIG. 6 shows a photograph of a front view of Test Sample 1 Impact 2 ofthe examples.

FIG. 7 shows a photograph of a rear view of Test Sample 1 Impact 2 ofthe examples.

FIG. 8 shows a photograph of a front view of Test Sample 1 Impact 3 ofthe examples.

FIG. 9 shows a photograph of a front view of Test Sample 1 Impact 4 ofthe examples.

FIG. 10 shows a photograph of a front view of Test Sample 2 Impact 1 ofthe examples.

FIG. 11 shows a photograph of a front view of Test Sample 2 Impact 2(comparative example, no mesh at joint) of the examples.

FIG. 12 shows a photograph of a front view of Test Sample 2 Impact 3 ofthe examples.

FIG. 13 shows a photograph of a rear view of Test Sample 2 Impact 3 ofthe examples.

FIG. 14 shows a photograph of a front view of Test Sample 2 Impact 4(comparative example) of the examples.

FIG. 15 shows a photograph of a front view of Test Sample 2 Impact 5(comparative example) of the examples.

FIG. 16 shows a photograph of a front view of Test Sample 2 Impact 6(comparative example) of the examples.

FIG. 17 shows a photograph of a rear view of Test Sample 2 Impact 6(comparative example) of the examples.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is an exterior sheathing building panel with animpact resistant woven mesh embedded in the gypsum core. The productwould be used on the exterior of a building to provide large scalemissile impact resistance as required in high velocity hurricane zones(HVHZ), coastal areas.

In particular, the present invention is a building panel suitable as anexterior sheathing panel comprising, from front to back:

-   -   a first fibrous mat,    -   a gypsum core layer having front and rear surfaces, the gypsum        core layer having a thickness of 0.5 to 1.25, preferably 0.5 to        1, inches, wherein the first fibrous mat is attached as a facer        cover sheet to the front surface of the gypsum core layer,    -   an impact resistant woven scrim mesh, embedded ¼ to 1/16 inch,        preferably ⅛ to 1/16 inch, from the rear surface of the gypsum        core layer,    -   a second fibrous mat attached as a backer cover sheet to the        rear surface of the gypsum core layer,    -   wherein the gypsum core layer comprises at least 75 wt. %        calcium sulfate material, wherein the gypsum core layer        comprises less than 5 wt. % magnesium oxide, preferably an        absence of magnesium oxide layer;    -   wherein the first fibrous mat and second fibrous mat        respectively comprise paper or fibrous material of at least one        of polymer fibers, glass fibers, mineral fibers or a combination        thereof,    -   wherein the impact resistant mesh has an Impact Range        Classification of >150 in-lbs (>17.0 J) (also known as        “Ultra-High”) according to ASTM E2486 (2018) Standard Test        Method for Impact Resistance of Class PB and PI Exterior        Insulation and Finish Systems (EIFS).

The rear mat is always partially embedded to bond the back facer to thepanel core. The mesh is always spaced from the rear mat to form a gapfilled with slurry to bond the mat to core bond. Typically the gap isabout 1/16 inch-⅛ inch embedment. The slurry penetration into the matranges from 40 to 60% of the mat thickness.

Typically the above-described impact resistant mesh has one or more,preferably all, of the following properties:

fabric surface weight of 20 to 30 ounces per square yard (690 to 1035g/m²) (measured according to ASTM D3776/D3776M-09a (2017), Standard TestMethods for Mass Per Unit Area (Weight) of Fabric, ASTM International,West Conshohocken, Pa., 2017),

a thickness of 0.040 to 0.045 inches (1.02 to 1.14 mm)(measuredaccording to ASTM D-1777-96 (2015), Standard Test Method for Thicknessof Textile Materials, ASTM International, West Conshohocken, Pa., 2015),and

a minimum tensile strength of 350 to 540 pounds-force per inch (2.41 to3.72 MPa) in the warp and weft, respectively (measured according to ASTMD-5035-11 (2019), Standard Test Method for Breaking Force and Elongationof Textile Fabrics (Strip Method), ASTM International, WestConshohocken, Pa., 2017).

In ASTM D3776/D3776M-09a (2017), Standard Test Methods for Mass Per UnitArea (Weight) of Fabric, ASTM International, West Conshohocken, Pa.,2017) fabric mass is calculated from the mass of a specimen the lengthand width of which have been measured as directed in one of theprocedures of Test Method D3773 and D3774-18.

ASTM D3773/D3773 M-10 (2019), Standard Test Methods for Length of WovenFabric, ASTM International, West Conshohocken, Pa., 2019 includes testmethods which cover four options for measuring fabric length and areapplicable to full rolls or bolts of materials. There are four approvedoptions of measuring length as follows: option A—hand, option B—drum,option C—clock, and option D—folding. The length is measured from oneend of the fabric to the other, using a suitable graduated device, orapparatus as described in the option used. The values stated in eitherSI units or in U.S. customary units shall be regarded separately asstandard. The values stated in each system may not be exact equivalents;therefore, each system must be used independently of the other, withoutcombining values in any way.

ASTM D3774-18, Standard Test Method for Width of Textile Fabric, ASTMInternational, West Conshohocken, Pa., 2018, includes a test methodwhich covers the measurement of the width of woven or knitted fabrics,usable width, or both. The method is applicable to full rolls, bolts offabric, and short specimens removed from a roll or bolt. Unlessotherwise specified, measurements shall include the selvages whenpresent. The method offers two options: Option A—Full Roll or Bolt orOption B—Short Specimen Removed from Full Roll or Bolt. The valuesstated in either SI units or U.S. customary units are to be regarded asstandard. The U.S. customary units may be approximate.

In ASTM D-1777-96 (2015), Standard Test Method for Thickness of TextileMaterials, ASTM International, West Conshohocken, Pa., 2015) a specimenis placed on the base of a thickness gauge and a weighted presser footlowered. The displacement between the base and the presser foot ismeasured as the thickness of the specimen. The test is conducted in thestandard atmosphere for testing textiles, which is 21+/−2° C. (70+/−2°F.) and 65+/−2% relative humidity (RH).

In ASTM D-5035-11 (2019), Standard Test Method for Breaking Force andElongation of Textile Fabrics (Strip Method), ASTM International, WestConshohocken, Pa., 2017) a test specimen is clamped in a tensile testingmachine and a force applied to the specimen until it breaks. Values forthe breaking force and elongation of the test specimen obtained frommachine scales, dials, autographic recording charts, or a computerinterfaced with the testing machine. This test method describesprocedures for carrying out fabric tensile tests using four types ofspecimen, and three alternative types of testing machines. Forreporting, use the following system to identify specific specimen andmachine combinations:

Type of specimen:

1R—25 mm (1.0 in.) raveled strip test

2R—50 mm (2.0 in.) raveled strip test

1C—25 mm (1.0 in.) cut strip test

2C—50 mm (2.0 in.) cut strip test

Type of tensile testing machine:

E—constant-rate-of-extension (CRE)

L—constant-rate-of-load (CRL)

T—constant-rate-of-traverse (CRT)

Possible combinations can be identified as follows in TABLE 1:

TABLE 1 Type of Tester Constant-Rate Constant-Rate Constant-Rate TestSpecimen of-Extension of-Load of-Traverse 25-mm (1-in.) raveled 1R-E1R-L 1R-T strip 50-mm (2-in.) raveled 2R-E 2R-L 2R-T strip 25-mm (1-in.)cut strip 1C-E 1C-L 1C-T 50-mm (2-in.) cut strip 2C-E 2C-L 2C-T

For example, 1R-E refers to a 25-mm (1-in.) raveled strip test carriedout on a constant-rate-of-extension tensile testing machine. This testmethod covers raveled strip and cut strip test procedures fordetermining the breaking force and elongation of most textile fabrics.The raveled strip test is applicable to woven fabrics while the striptest is applicable to nonwoven fabrics, felted fabrics, and dipped orcoated fabrics. The values stated in either SI units or in U.S.customary units shall be regarded separately as standard. The valuesstated in each system may not be exact equivalents; therefore, eachsystem must be used independently of the other, without combining valuesin any way.

In particular, the exterior sheathing building panel of the inventionmeets 2017 Florida Building Code Test—Protocols for High-VelocityHurricane Zone, Chapter 16, Section 1626, Sixth Edition, to be capableof resisting a 2 inches×4 inches (51 mm×102 mm) missile weighing 9pounds (4.1 kg) in accordance with 2017 Florida Building CodeTest—Testing Application Standard (TAS) 201-94 Impact Test Procedures.Per Section 1626.2.4, the missile shall impact the surface of each testspecimen at a speed of 50 feet per second (34 miles per hour; 15.2 m/s).Typically this missile is a 2 inch (5.08 cm)×4 inch (10.16 cm)×8 foot(234 cm) wood stud.

FIG. 1 shows a perspective view of an exterior sheathing building panel2 of the present invention which is a gypsum panel. The exteriorsheathing building panel 2 has a gypsum core 4 and front facing 5 on itsfront side and rear facing 6 on its rear side. The impact resistantwoven mesh 8 is embedded in the core 4 near, but spaced from, the rearfacing at the rear side of the panel 2. The impact resistant woven mesh8 is positioned in a plane that is substantially parallel to both thefront facing 5 and rear facing 6. The front facing 5 and rear facing 6may be respective paper sheets, but are preferably respective fibrousmats.

FIG. 2 shows a cross-sectional view of the exterior sheathing panel 2 ofthe present invention of FIG. 1 .

The impact resistant woven mesh 8 is embedded a distance “D” of ¼ to1/16 inch (6.35 to 1.59 mm), preferably ⅛ to 1/16 inch (3.175 to 1.59mm), from the cementitious layer rear surface.

The impact resistant woven mesh 8 is embedded in the core 4 near, butspaced from, the rear facing 6 at least 1/16 inch (1.59 mm), typically ⅛to 1/16 inch (3.175 to 1.59 mm).

The core of the gypsum panel comprises set gypsum, namely calciumsulfate dihydrate. This results from setting a gypsum slurry comprisingcalcium sulfate hemihydrate.

Fibrous Mat Facings

The first fibrous mat and second fibrous mat facings (also known ascover sheets) are located at the faces of the exterior sheathingbuilding panels of the present invention. It will be appreciated thateach fibrous mat has two facing surfaces: an outwardly facing surfaceand a surface facing the gypsum core.

The first fibrous mat and second fibrous mat respectively comprise paperor fibrous material selected from at least one of polymer fibers, glassfibers, mineral fibers or a combination thereof.

Although sheathing can be made with water resistant paper facers, formold resistance, non-paper designs are preferred as they are more robustto the elements and mold growth resistance. Thus, preferably the gypsumexterior sheathing building panels of the invention have an absence ofpaper front and back facings. Thus, preferably the first fibrous mat andsecond fibrous mat of the gypsum exterior sheathing building panels arerespectively fibrous material selected from at least one of polymerfibers, glass fibers, mineral fibers or a combination thereof. Morepreferably the gypsum exterior sheathing building panels of theinvention as a whole have an absence of paper. Preferably the gypsumexterior sheathing building panels of the invention have an absence ofcellulose, particularly an absence of cellulose fibers.

The fibrous mat can comprise any suitable type of polymer fiber, glassfiber, mineral fiber, or combination thereof. The choice of fibers willdepend, in part, on the type of application in which the cementitioussheathing panel is to be used. For example, when the sheathing panel isused for applications that require heat or fire resistance, appropriateheat or fire resistant fibers should be used in the fibrous mat.

Mineral fibers are fibrous inorganic substances made primarily fromrock, clay, slag, or glass. These fibers are classified into threegeneral groups: fiberglass (glass wool and glass filament), mineral wool(rock wool and slag wool), and refractory ceramic fibers (RCF).

Examples of fiber materials suitable for use in the fibrous mat include,but are not limited to, glass fibers, polyamide fibers, polyaramidfibers, polypropylene fibers, polyester fibers (e.g., polyethyleneterephthalate (PET)), polyvinyl alcohol (PVOH), polyvinyl acetate(PVAc), and combinations thereof. Preferably the fibers consist ofcoated or uncoated glass fibers (also known as coated or uncoatedfiberglass). Typically the fibers consist of coated or uncoated alkalineresistant glass fibers (also known as coated or uncoated alkalineresistant fiberglass).

The fibrous mats can be woven or non-woven. However, non-woven mats arepreferred. The non-woven mat typically has a small amount of binderhomogeneously dispersed therethrough. The binder can be any bindertypically used in the mat industry. Suitable binders include, withoutlimitation, urea formaldehyde, melamine formaldehyde, stearated melamineformaldehyde, polyester, acrylics, polyvinyl acetate, urea formaldehydeor melamine formaldehyde modified or blended with polyvinyl acetate oracrylic, styrene acrylic polymers, and the like, as well as combinationsthereof. Suitable fibrous mats include commercially available mats usedas facing materials for cementitious exterior sheathing panels.

Furthermore, the fibers of the mat can be hydrophobic or hydrophilic,coated or uncoated.

Uncoated mat is typically about 12 to about 30, more typically 12 to 25,most typically 14 to 20 lbs/MSF. Uncoated mat includes the fibers and apolymer binder. For purposes of the present specification the term“pre-coated non-woven glass fiber mat” typically is a mat having acoating of about 45 lbs/MSF to about 60 lbs/MSF, wherein the coatinguniformly penetrates the glass mat substrate from one side of the coatedglass mat to a depth which is a fraction of the thickness of the coatedglass mat. Thus, in addition to the at most small amount ofsubstantially uniformly distributed polymer binder which an uncoated mathas, a pre-coated mat has an additional binder coating of polymer binderand inorganic filler applied to one side to penetrate at most partiallythrough the thickness of the mat. Thus, a pre-coated non-woven glassfiber mat has one side coated with the binder coating and the other sideuncoated to expose a raw glass fiber side. The term “pre-coated” isemployed in the present specification where the non-woven glass fibermat is coated with the binder coating before contacting a cementitiousaqueous slurry that will become a core of a board.

When employing a pre-coated mat if a hydrophobic finish compositionlayer is also employed then the hydrophobic finish composition layer isadhered to the coated surface of the coated fibrous mat rather than theraw glass fiber side. The cementitious-based core is adhered to the rawglass fiber side.

A pre-coated mat differs from an uncoated mat. For example, an acrylicpre-coated glass mat differs from an “uncoated” glass mat using acrylicbinder.

For purposes of the present specification an uncoated glass fiber mat istypically a glass fiber mat having an overall weight of 15-40 lbs/MSFand has at most a small amount of polymer binder substantially uniformlydistributed, for example 19-27 wt % of the overall mat is polymerbinder, but there is no inorganic filler. The thickness of an uncoatedglass mat is typically 20-40 mil.

Also, a pre-coated mat is heavier than the uncoated mat. A pre-coatedmat, in addition to the weight of the non-woven glass mat substrate, has40-165 lbs./MSF (pounds per thousand square feet) of binder coatingcoated on one side of the non-woven glass mat substrate. The weight ofthe non-woven glass mat substrate prior to applying the binder coatingis 10-50 lbs./MSF. Thus, after applying the binder coating to make thepre-coated glass mat the weight of this pre-coated glass mat is 50-215lbs./MSF. Preferably the non-woven glass mat substrate before coatingweighs between about 12 and about 50 lbs./MSF, more preferably about14.5-26.5 lbs./MSF. Preferably 50-100 lbs./MSF, more preferably 61 to 75lbs./MSF, of binder coating is coated on one side of the non-woven glassmat substrate. On average, the weight of the coated glass mat per unitarea is no more than about six times the weight of the glass matsubstrate prior to coating. The coating preferably also imparts atensile strength to the coated glass mat which on average is at least1.33 times greater than the tensile strength of the glass mat substratewithout the coating.

The binder coating comprises binder polymer and inorganic filler. Thebinder coating is substantially uniformly distributed across the oneside of the mat. Thus, the binder coating only partially permeates intothe glass mat substrate. The other side exposes raw glass fibers coatedat most with a small amount of binder polymer and no inorganic filler.The binder coating uniformly penetrates the glass mat substrate to adesired fractional thickness of the coated glass mat. The penetration ofthe binder coating into the glass mat substrate extends a depth of from10% of a thickness of the coated glass mat to 75% of the thickness ofthe coated glass mat.

Gypsum Core

The gypsum core of the gypsum exterior sheathing building panelprimarily comprises calcium sulfate material, along with any suitableadditives.

A gypsum panel useful in the present invention comprises a gypsum corecomprising greater than 75 weight % calcium sulfate material, typicallyat least 85 weight % calcium sulfate material, more typically at least95 weight % calcium sulfate material. Generally the gypsum panel usefulin the present invention comprises a gypsum core comprising greater than75 weight % calcium sulfate dihydrate, typically at least 85 weight %calcium sulfate dihydrate, more typically at least 90 weight % calciumsulfate dihydrate, most typically at least 95 weight % calcium sulfatedihydrate.

A typical gypsum panel core is made from setting an aqueous gypsumslurry mixture having over 90 wt. %, more typically over 95 wt. %calcium sulfate hemihydrate (stucco) on a dry (water free) basis.

Suitable calcium sulfate material include any one or more ofwater-soluble calcium sulfate anhydrite, calcium sulfatealpha-hemihydrate, calcium sulfate beta-hemihydrate, natural, syntheticor chemically modified calcium sulfate hemihydrates “calcined gypsum”),calcium sulfate dihydrate (“gypsum,” “set gypsum,” or “hydratedgypsum”), and mixtures thereof. As used herein, the terms “calciumsulfate” or “calcium sulfate material” refer to any of the forms ofcalcium sulfate referenced above.

Preferably the cores of the gypsum boards of the invention have lessthan 10 wt. % magnesium oxide. More preferably the cementitious cores ofthe gypsum boards and cement boards of the invention have less than 5wt. % magnesium oxide. Most preferably the cementitious cores of thegypsum boards and cement boards of the invention have an absence ofmagnesium oxide.

The gypsum core can be of any type or shape suitable for the exteriorsheathing building panel of the present invention. Non-limiting examplesof such building panels include gypsum panels of any size and shape. Atypical gypsum panel, including its core and facings, is a ½″ to 1.25″(1.27 to 3.175 cm), most typically about ⅝ inches (1.6 cm), thick coatedglass-mat board.

The overall thickness of the exterior sheathing building panel cangenerally be any thickness commonly used in the construction industry.Generally, the exterior sheathing building panel can be about ½ inch(1.27 cm) to 1.25 inch (3.175 cm) in thickness, typically about ½ inch(1.27 cm) to about 1 inch (2.54 cm), more typically about ½ inch (1.27cm) to about ¾ inch (1.90 cm). For example, the exterior sheathingbuilding panel can have a thickness of about ½ inch (1.27 cm), about ⅝inch (1.6 cm), about ¾ inch (1.90 cm), or about 1 inch (2.54 cm).

The width of the exterior sheathing building panel can generally be anywidth commonly used in the construction industry. For example, the widthcan be about 32 inches (81 cm), about 36 inches (91 cm), about 48 inches(122 cm), or about 54 inches (137.2 cm).

The length of the exterior sheathing building panel can generally be anylength commonly used in the construction industry. For example, thelength can be about 60 inches (152 cm), about 72 inches (183 cm), about96 inches (244 cm), about 120 inches (304 cm), and 144 inches (366 cm).

Optionally the gypsum core comprises hydraulic cement. However,typically there is less than 10 wt′%, less than 5 wt. % or an absence ofhydraulic cement

ASTM defines “hydraulic cement” as follows: a cement that sets andhardens by chemical interaction with water and is capable of doing sounder water. There are several types of hydraulic cements that are usedin the construction and building industries. While calcium sulfatehemihydrate does set and harden by chemical interaction with water, itis not included within the broad definition of hydraulic cements in thecontext of this invention. All of the aforementioned hydraulic cementscan be used to make the panels of the invention.

Suitable hydraulic cements include any one of more of Portland cement,sorrel cement, fly ash cement, slag cements such as blast-furnace slagcement and super-sulfated cements, calcium sulfoaluminate cement,calcium alumina cement, expansive cements, white cement, and rapidsetting and hardening cements. The most popular and widely used familyof closely related hydraulic cements is known as Portland cement. ASTMdefines “Portland cement” as a hydraulic cement produced by pulverizingclinker consisting essentially of hydraulic calcium silicates, usuallycontaining one or more of the forms of calcium sulfate as an intergroundaddition.

Other additives can be included as desired, including, for example,starch for enhancing the strength of the board (e.g., non-migratingstarches such as pregelatinized starch, ethoxylated starches, etc),dispersant (e.g., naphthalene sulfonate), polyphosphate (e.g., sodiumtrimetaphosphate), accelerator (e.g., heat resistant accelerator),retarder, water resistance additive (e.g., siloxane), fire resistanceadditive (e.g., vermiculite, ATH), etc. The additives for thecementitious core can be any additives commonly used to produce fibrousmat-faced gypsum panels. Such additives include, without limitation,structural additives such as mineral wool, continuous or chopped glassfibers (also referred to as fiberglass), perlite, clay, vermiculite,calcium carbonate, polyester, and paper fiber, as well as chemicaladditives such as foaming agents, fillers, accelerators, sugar,enhancing agents such as phosphates, phosphonates, borates and the like,retarders, binders (e.g., starch and latex), colorants, fungicides,biocides, and the like. However, there may be an absence of any one ormore of these additives.

If desired, an antimicrobial/antifungal agent is added to a cementitiouscore for the gypsum panel and/or a cover sheet. Suitable antimicrobialagents include 2-(4-thiazolyl) benzimidazole, silver zeolite, zinc oxideand zinc pyrithione. However, there may be an absence of any one or moreof these additives.

Advantageously, the cementitious core also comprises a hydrophobicagent, such as a silicone-based material (e.g., a silane, siloxane, orsilicone-resin matrix), in a suitable amount to improve the waterresistance of the core material. It is also preferred that thecementitious core comprise a siloxane catalyst, such as magnesium oxide(e.g., dead burned magnesium oxide), fly ash (e.g., Class C fly ash), ora mixture thereof. The siloxane and siloxane catalyst can be added inany suitable amount, and by any suitable method as described herein withrespect the method of preparing a water-resistant fibrous mat-facedcementitious panel of the invention, or as described, for example, inU.S. Patent Publications 2006/0035112 A1 or 2007/0022913 A1. Desirably,the cementitious core also comprises strength-improving additives, suchas phosphates (e.g., polyphosphates as described in U.S. Pat. Nos.6,342,284, 6,632,550, and 6,800,131 and U.S. Patent Publications2002/0045074 A1, 2005/0019618 A1, and 2007/0022913 A1) and/orpre-blended unstable and stable soaps (e.g., as described in U.S. Pat.Nos. 5,683,635 and 5,643,510). However, there may be an absence of anyone or more of these additives.

The cementitious core can comprise paper or glass fibers, but ispreferably substantially free of paper and/or glass fibers (e.g.,comprises less than about 1 wt. %, less than about 0.5 wt. %, less thanabout 0.1 wt. %, or even less than about 0.05 wt. % of paper and/orglass fibers, or contains no such fibers). However, preferably there isan absence of cellulose.

Impact Resistant Mesh

The impact resistant woven mesh embedded in the core material willprovide mechanical properties to the exterior sheathing building panelof the present invention.

In the invention “mesh” and “mat” are separate terms. A “Mesh”, alsoknown as a scrim, is a woven open grid mat used for embedding in thecore. Mesh is used for the impact resistant woven mesh of the buildingpanels of the invention. A “Mat” is woven or non-woven, preferablynon-woven, sheet that is much tighter to prevent bleed through or slurrypenetration during production. Mat is used for the cover sheets of thebuilding panels of the invention.

The impact resistant woven mesh is made of woven fibers in the form ofyarns or rovings woven together in any number of formations. Yarnscomprise a group of individual fibers bundled together, normally by atwisting process, to form each yarn. Instead of yarns, rovings can alsobe used to form the woven scrim. Rovings are formed by laying theindividual fibers together in a substantially parallel fashion andbinding them together through known binding techniques. Either yarns orrovings may be used to create the woven scrims and the term “end”, asused herein, shall mean either yarns or rovings. In addition, whilemeasurements disclosed herein refer to yarns (e.g., yarns per inch), itwill be understood that the same measurements apply to rovings.

The impact resistant woven mesh fibers can be synthetic polymer fibers,basalt fibers, carbon fibers, or alkaline resistant glass fibers.Typical synthetic polymer fibers are polyamide fibers, especially aramidfibers, for example, KEVLAR fibers, TWARON fibers, NOMEX fibers, orTECHNORA fibers. Also suitable can be natural fibers that are free ofunsuitable contamination, such as hazardous impurities.

The impact resistant mesh, embedded ¼ to 1/16 inch, preferably ⅛ to 1/16inch, from the cementitious layer surface, has an Impact RangeClassification of >150 in-lbs (>17.0 J) (also known as “Ultra-High”)according to ASTM E2486/E286M-13 (Reapproved 2018) Standard Test Methodfor Impact Resistance of Class PB and PI Exterior Insulation and FinishSystems (EIFS). This test subjects specimens to deformation by a fallingstandard weight. The impact resistance classification is determined bythe number of joules (inch-pounds) achieved when at least six out of tentests do not display broken reinforcing mesh visible to the naked eyeunder normal lighting conditions.

The test employs test apparatus as specified in the Apparatus Section ofTest Method ASTM D2794-93 (2019) Standard Test Method for Resistance ofOrganic Coatings to the Effects of Rapid Deformation (Impact), ASTMInternational, West Conshohocken, Pa., 2019, except that the cylindricalweight shall be 1.82 kg (4.0 pounds), the EIFS (Exterior Insulation andFinish Systems) specimen shall fit below the tube, and the diameter ofthe hemispherical head of a steel punch used as an indenter shall be 13mm (1.2 inches) and it shall be made to fit inside the guide tubeinstead of resting on the test panel. The test apparatus as specified inthe Apparatus Section of Test Method D2794-1993 R19 Edition StandardTest Method for Resistance of Organic Coatings to the Effects of RapidDeformation (Impact) consists of a vertical tube to guide a cylindricalweight that is dropped on a steel punch resting on a test panel. Thevertical tube (guide tube) is 24 to 48 inch (0.6 to 1.2 m) long mountedvertically on a base plate. A slot is cut lengthwise on one side of thetube to act as a guide for a cylindrical weight inside the tube.Graduations are marked in inch pounds along the slot. The base is madesuch that the EIFS specimen can be inserted at 2 inches (50 mm) belowthe tube. The weight fits inside the guide tube. A pin is fitted intoone side of the weight to act as a guide by riding in the slot of thetube and to serve as a handle by which the weight can be raised andreleased and serve as the indicator of inch-pounds (kilogram-meters).There is also an indenter which is the steel punch with a hemisphericalhead. The punch is held vertically by the guide ring. There is also apanel support which is a steel fixture with a 0.64 inch (16.3 mm)diameter cylindrical hole centered under the indenter for supporting thetest panel.

The test specimen has an EIFS (Exterior Insulation and Finish Systems)base coat, reinforcing mesh, and finish coat applied to 600 by 1200 mm(2 by 4 foot) sections of 25-mm (1-in) thick insulation board. (EIFSterminology is known according to ASTM E2110-17 Standard Terminology forExterior Insulation and Finish Systems (EIFS), ASTM International, WestConshohocken, Pa. (2017)). This terminology covers terms and definitionspertaining to materials and processes used in the design and applicationof exterior insulation and finish systems (EIFS). The reinforcing meshis continuous with no laps or joints. A base coat is the initialwet-state material, either factory or field-mixed, used to encapsulatethe nonmetallic reinforcing mesh or fasten the insulation to thesubstrate. The reinforcing mesh is nonmetallic reinforcing mesh whichis, for example, fiberglass, component of the EIFS. In the inventionthis mesh is encapsulated in the gypsum core to strengthen the system.The finish coat is the final wet-state material, which provides colorand texture, applied over the base coat.

The specimens are allowed to cure at least 298 days at 22+/−3° C.(72+/−5° F.) and 50+/−5% % relative humidity. The test is performed inthe same environment or immediately after removal. In this test thetester weighs the specimens and records the type and density of theinsulation board of the specimens. The specimens, with the coated sideup, are placed flat against a smooth, flat rigid surface. The weight isput into the tube up to the minimum value of the impact range where itis expected that less than 40% of the ten tests will fail. The StandardImpact Resistance Impact Range Classification has an Impact Range of2.8-5.6 J (25-49 inch-pounds). The Medium Impact Resistance Impact RangeClassification has an Impact Range of 5.7-10.1 J (50-89 inch-pounds).The High Impact Resistance Impact Range Classification has an ImpactRange of 10.2-17.0 J (90-150 inch-pounds). The Ultra-High ImpactResistance Impact Range Classification has an Impact Range of Over 17.0J (150 inch-pounds). Then the weight is released to drop from the tubeonto the test panel specimen. Ten tests are performed at the minimumvalue. No impacts are within 100 mm (4 inches) from the edges of thespecimen or within 100 mm (4 inches) of a prior impact). Then thespecimen is removed from the support surface and observed to determineif the impact area has any broken reinforcing mesh. If there is breakagein more than four of ten tests then the test is repeated at the nextlower range.

Typically the above-described impact resistant mesh has one or more ofthe following properties:

fabric surface weight of 20 to 30 ounces per square yard (690 to 1035g/m²) (measured according to ASTM D3776/D3776M-09a (2017), Standard TestMethods for Mass Per Unit Area (Weight) of Fabric, ASTM International,West Conshohocken, Pa., 2017),

a thickness of 0.040 to 0.045 inches (1.02 to 1.14 mm)(measuredaccording to ASTM D-1777-96 (2015), Standard Test Method for Thicknessof Textile Materials, ASTM International, West Conshohocken, Pa., 2015),and

a minimum tensile strength of 350 to 540 pounds-force per inch (2.41 to3.72 MPa) in the warp and weft, respectively (measured according to ASTMD-5035-11 (2019), Standard Test Method for Breaking Force and Elongationof Textile Fabrics (Strip Method), ASTM International, WestConshohocken, Pa., 2017).

The impact resistant woven mesh can be strengthened by coating theimpact resistant woven mesh with a resin.

Generally the impact resistant woven mesh will have a higher arealweight and higher minimum tensile strength in the warp and weft than therespective facer mats.

The mesh size of the impact resistant woven mesh should allow the gypsumslurry to pass through the scrim. The nominal construction or nominalmesh size is typically measured by yarns per inch and is given as anumber by number value that corresponds to the number of weft yarns andwarp yarns present in an inch of the scrim.

The impact resistant woven mesh may be any of a number of types of wovenscrim patterns, including, a leno scrim, a plain woven scrim, a basketwoven scrim, a mock leno woven scrim, a twill woven scrim, or a satinwoven scrim.

A leno scrim has “fill” or “weft” ends (i.e., horizontal ends) that arewrapped and/or twisted around “warp” ends (i.e., vertical ends) to lockthe ends in place in a woven configuration. While a leno scrim cancomprise ends made from any number of materials, it is preferred thatthe ends of the leno scrim be made up of fiberglass. A plain woven scrimconfiguration has ends that cross over and under one another to createthe woven scrim. A basket woven scrim configuration has sets of two weftends that cross over and under other sets of two warp ends to create thewoven scrim. A mock leno woven scrim configuration has ends that run ingroups both vertically and horizontally, locking each other in place atthe interlacing. A twill woven scrim configuration has interlacing ofthe ends arranged to form a distinct diagonal line on the scrim surface.A satin woven scrim configuration has warp ends that cross over three ormore consecutive weft ends, then under the next weft end, back overthree or more consecutive weft ends, and such pattern is repeated untilthe scrim is completed. Similarly, the weft ends of the satin wovenscrim passes over three or more of consecutive warp ends, then under thenext warp end, back over three or more consecutive warp ends, and suchpattern is repeated until the scrim is completed. While severalexemplary woven scrims are described herein, it will be appreciated byone skilled in the art that any type of woven scrims can be used.

A. Methods of Making Building Panels

The invention makes the building panels by the following steps.

-   -   depositing a first fibrous mat as a face mat on a surface,    -   mixing at least water and calcium sulfate material to prepare an        aqueous gypsum slurry comprising at least 75 wt. % calcium        sulfate material on a dry (water free) basis, wherein said        calcium sulfite material comprises calcium sulfate hemihydrate,    -   wherein the aqueous gypsum slurry comprises less than 10 wt. %        magnesium oxide on a dry (water free) basis, preferably less        than 5 wt. % magnesium oxide on a dry (water free) basis, most        preferably an absence of magnesium oxide;    -   applying the aqueous slurry in a bonding relation to the face        mat to form a gypsum core layer, the gypsum core layer having a        face side and a back side, wherein the gypsum core layer face        side faces said face mat;    -   applying an impact resistant woven scrim mesh on the back side        of the gypsum core layer to embed the impact resistant woven        scrim mesh into the gypsum core layer;    -   applying a second fibrous mat as a back mat on the back side of        the gypsum core layer having the embedded impact resistant mesh        to form a board precursor, thereby locating the aqueous slurry        between the face mat and the back mat;    -   allowing the aqueous slurry located between the face mat and the        back mat to set, thereby forming the building panel.

The gypsum core of the gypsum panel comprises set gypsum, namely calciumsulfate dihydrate resulting from setting the aqueous gypsum slurrycomprising calcium sulfate hemihydrate and optionally calcium sulfateanhydrite.

Although the aqueous slurry being deposited is known as aqueous gypsumslurry the majority, generally at least 70 wt. %, of the calcium sulfatematerial it contains when deposited is calcined gypsum (calcium sulfatehemihydrate) which will set during processing to convert to gypsum(calcium dihydrate). Typically the aqueous gypsum slurry contains 75 to100 wt. % reactive powder on a dry (water free) basis, to provide theaqueous gypsum slurry with at least 75 wt. % calcium sulfate material ona dry (water free) basis, preferably at least 75 wt. % calcium sulfatehemihydrate on a dry (water free) basis.

Typically when the calcium sulfate material and water are mixed theresulting aqueous gypsum slurry has at least 75 wt. %, preferably atleast 85 wt. %, most preferably at least 95 wt. %, on a dry basiscalcium sulfate hemihydrate. In other words, the aqueous gypsum slurryis at least 75 wt. %, preferably at least 85 wt. %, most preferably atleast 95 wt. %, on a dry basis calcium sulfate hemihydrate prior tosetting.

In the invention the cementitious slurry preferably does not entirelypenetrate the first and second fibrous mats. Preferably, thecementitious slurry penetrates 30-60% of the thickness of each mat, morepreferably 40-60% of the thickness of each mat.

The manufacturing method of the gypsum exterior sheathing buildingpanels of the present invention typically involves depositingcementitious slurry (e.g., a mixture containing stucco and water, wherestucco refers to calcined gypsum, typically comprised primarily ofcalcium sulfate hemihydrate and optionally calcium sulfate anhydrite)over a first mat facing material and covering the wet slurry, thenembedding the impact resistant mesh, and then covering the wet slurrywith a second mat facing material, such that the cementitious slurry andimpact resistant mesh are sandwiched between the two mat facingmaterials. The cementitious slurry is allowed to harden (e.g., set toform an interlocking matrix of calcium sulfate dihydrate, referred to asset gypsum) to produce a solid article prior to final drying in a kiln.

Methods of preparing the fibrous mat-faced cementitious gypsum panelaccording to the invention typically comprise placing a bottom facingmaterial (that will become the front facing) onto a conveyor belt, oronto a forming table that rests on the conveyer belt, and transportingthe bottom facing material by the conveyor belt so that it passesunderneath an aqueous slurry discharge. The aqueous slurry is dischargedfrom a mixer through the mixer's discharge conduit or boot, whichspreads the slurry on the bottom facing material. Once the aqueousslurry is deposited on the bottom facing material, a moving continuousimpact resistant woven mesh is placed on top of the slurry and bottomfacing material through the use of a conveyor system. The aqueous gypsumslurry passes through the openings of the impact resistant woven meshand the impact resistant woven mesh becomes embedded into the slurry.

A moving, continuous top facing material (that will become the rearfacing) is placed on top of the embedded impact resistant woven mesh,the slurry and bottom facing material through the use of anotherconveyor system. In this manner, the slurry with the embedded impactresistant woven mesh is positioned in between the top and bottom facingmaterials to form the gypsum building panel; so that, as shown in FIG. 2, the embedded impact resistant woven mesh is in a parallel plane andnear and/or adjacent to the top facing material. The building panel canthen pass through a forming station, which forms the wallboard to thedesired thickness and width. The panel then sets and dries.

A typical method for preparing a cementitious gypsum panel of theinvention can be conducted on existing gypsum board manufacturing linesused to make fibrous mat-faced cementitious boards known in the art.Briefly, the process typically involves discharging a fibrous matmaterial onto a conveyor, or onto a forming table that rests on aconveyer, which is then positioned under the discharge conduit (e.g., agate-canister-boot arrangement as known in the art, or an arrangement asdescribed in U.S. Pat. Nos. 6,494,609 and 6,874,930) of a mixer. Thecomponents of the cementitious slurry are fed to the mixer comprisingthe discharge conduit, where they are agitated to form the cementitiousslurry. Foam can be added in the discharge conduit (e.g., in the gate asdescribed, for example, in U.S. Pat. Nos. 5,683,635 and 6,494,609).

The aqueous gypsum slurry can be deposited onto the fibrous mat facingmaterial in accordance with known methods and on existing manufacturinglines for preparing a fibrous mat-faced cementitious panel. Forinstance, when the aqueous gypsum slurry is discharged onto the fibrousmat facing material, the slurry is spread, as necessary, over thefibrous mat facing material. Once the slurry is deposited on the bottomfacing material, a moving continuous woven scrim is placed on top of theslurry and bottom facing material through the use of a conveyor system.The slurry passes through the openings of the scrim and the scrimbecomes embedded into the slurry. Then a second facing material, whichmay be a fibrous mat or other type of permeable facing material (howeverpreferably not paper), is placed on top of the embedded scrim. The wetcementitious assembly thereby provided is conveyed to a forming stationwhere the article is sized to a desired thickness, and to one or moreknife sections where it is cut to a desired length to provide acementitious board. The fibrous mat-faced cementitious panel is allowedto harden, and, optionally, excess water is removed using a dryingprocess (e.g., by air-drying or transporting the fibrous mat-facedcementitious panel through a kiln). In particular, the gypsum buildingpanel travels along a belt line for several minutes, during which timethe rehydration reaction occurs and the board stiffens. The gypsumbuilding panels are then cut into a desired length and fed into a large,continuous kiln for drying. During drying, the excess water (free water)is evaporated from the gypsum core while the chemically bound water isretained in the newly formed gypsum crystals.

Each of the above steps, as well as processes and equipment forperforming such steps, are known in the art.

It also is common in the manufacture of cementitious building panelssuch as gypsum building panels to deposit a relatively dense layer ofslurry onto the first facing material before depositing the primaryslurry, and to use vibration in order to eliminate large voids or airpockets from the deposited slurry. Also, hard edges, as known in theart, are sometimes used. These steps or elements (dense slurry layer,vibration, and/or hard edges) optionally can be used in conjunction withthe invention.

Thus, optionally, a dense gypsum layer can be applied in between thecore and the face mat, and optionally between the core and the back mat.For example, stucco and water are inserted into the main mixer, whilefoam is inserted downstream in the discharge conduit, meaning that foamis not inserted in the main mixer body. The main mixer can be a pinmixer or a pin-less mixer, as desired. A portion of the slurry, which isessentially foamless, is diverted from the mixer from an exit portgenerally opposite the discharge conduit to form the concentrated layerslurry. The main mixer acts as a pump to drive the unfoamed slurry outthe smaller discharge port for the dense slurry which flows through thepressurized slurry line. Additives in wet form are injected into thepressurized slurry line through injection ports. The line is desirablylong enough, which is within the level of ordinary skill, to allow foruniform mixing of slurry and additives. There is no need for separateintroduction of stucco or water. If desired, two mixers can be used,with the second mixer for separately formulating a dense layer (skimcoat or skim layer), e.g., with less or no foam, to be deposited betweenthe core and one or both mats.

If desired to provide further water resistance to the fibrous mat-facedcementitious gypsum panel the method of making the fibrous mat-facedcementitious panel may further comprise (a) preparing an aqueoussiloxane dispersion comprising about 4 wt. % to about 8 wt. % siloxanein water, and (b) combining the siloxane dispersion with thecementitious mixture to provide the cementitious slurry to be depositedonto a facing or other type of substrate, and subsequently allowed toharden, thereby providing the fibrous mat-faced cementitious panel.

System

In another aspect, the present disclosure is directed to a systemcomprising framing to which is attached at least one exterior sheathingbuilding panel of the invention which provides impact resistance. Inparticular, the invention provides an exterior sheathing panelcomprising, from front to back:

-   -   a first fibrous mat,    -   a gypsum core layer having front and rear surfaces, the gypsum        core layer having a thickness of 0.5 to 1.25, preferably 0.5 to        1, inches, wherein the first fibrous mat is attached as a facer        cover sheet to the front surface of the gypsum core layer,    -   an impact resistant woven scrim mesh, embedded ¼ to 1/16 inch,        preferably ⅛ to 1/16 inch, from the rear surface of the gypsum        core layer,    -   a second fibrous mat attached as a backer cover sheet to the        rear surface of the gypsum core layer,    -   wherein the gypsum core layer comprises at least 75 wt. %        calcium sulfate material, wherein the gypsum core layer        comprises less than 10 wt. % magnesium oxide, preferably less        than 5 wt. % magnesium oxide, most preferably an absence of        magnesium oxide;    -   wherein the first fibrous mat and second fibrous mat        respectively comprise paper or fibrous material of at least one        of polymer fibers, glass fibers, mineral fibers or a combination        thereof,    -   wherein the impact resistant mesh has an Impact Range        Classification of >150 in-pounds (>17.0 J) (also known as        “Ultra-High”) according to ASTM E2486 (2018) Standard Test        Method for Impact Resistance of Class PB and PI Exterior        Insulation and Finish Systems (EIFS).

Typically the above-described impact resistant mesh has one or more,preferably all, of the following properties:

fabric surface weight of 20 to 30 ounces per square yard (690 to 1035g/m²) (measured according to ASTM D3776/D3776M-09a (2017), Standard TestMethods for Mass Per Unit Area (Weight) of Fabric, ASTM International,West Conshohocken, Pa., 2017),

a thickness of 0.040 to 0.045 inches (1.02 to 1.14 mm)(measuredaccording to ASTM D-1777-96 (2015), Standard Test Method for Thicknessof Textile Materials, ASTM International, West Conshohocken, Pa., 2015),and

a minimum tensile strength of 350 to 540 pounds-force per inch (2.41 to3.72 MPa) in the warp and weft, respectively (measured according to ASTMD-5035-11 (2019), Standard Test Method for Breaking Force and Elongationof Textile Fabrics (Strip Method), ASTM International, WestConshohocken, Pa., 2017).

In particular, the exterior sheathing building panel of the inventionmeets 2017 Florida Building Code Test—Protocols for High-VelocityHurricane Zone, Chapter 16, Section 1626, Sixth Edition, to be capableof resisting a 2 inches×4 inches (51 mm×102 mm) missile weighing 9pounds (4.1 kg) in accordance with 2017 Florida Building CodeTest—Testing Application Standard (TAS) 201-94 Impact Test Procedures.Per Section 1626.2.4, the missile shall impact the surface of each testspecimen at a speed of 50 feet per second (34 miles per hour; 15.2 m/s).Typically this missile is a 2 inch×4 inch×8 foot wood stud.

Thus, generally, exterior sheathing building panel of the invention arecapable of preventing panel penetration by an eight foot long two inchby four inch missile (projectile such as a 2 inch×4 inch×8 foot woodstud) weighing about 9 pounds (4.1 kg) and impacting the panel faceendwise at 34 miles per hour. Generally exterior sheathing buildingpanel of the invention are also capable of providing a vacuum resistancethrough the panel after impact of at least one-third the resistanceprior to impact, which was in excess of 90 psf.

Any of the integrated panels described herein can be part of a systemthat includes an integrated panel that is adhered to one or more wallstuds or ceiling joists via a fastener (e.g., a screw, a nail) with therear mat facing the wall studs or ceiling joists. Two adjacent panelsare joined at the seams using a suitable joint tape and joint compound.If desired, an additional flashing layer can be added as an air andwater barrier. A cladding material (e.g., siding, shingle, stone) isfurther adhered to the exterior facing surface of the integrated panel.

FIG. 3 is a perspective view of a typical exterior sheathing system 20that may be employed in the present exterior wall system. FIG. 3 showsan exterior sheathing panel 2 of the present invention attached to oneside of a metal stud wall suitable in the exterior wall system of thepresent invention, wherein the exterior sheathing panel includes acementitious panel selected from a gypsum panel (for example a panel ofFIG. 2 ). FIG. 3 shows metal stud wall “skeleton” 22 which includes aplurality of metal studs 24, an upper track 26, a lower track 28.Sheathing panels 2 may be secured in any known manner to one or bothsides of the metal studs 24 to close the wall and form the exteriorsurface or surfaces of the wall. A typical metal stud wall “skeleton”may be fabricated according to U.S. Pat. No. 6,694,695 to Collins etal., incorporated herein by reference, which is suitable for combinationwith an exterior sheathing panel to achieve an exterior wall system ofthe present invention. This metal frame system is merely provided asillustrative as other metal frames may also be employed. Or a wood framemay be employed.

In the system the exterior sheathing panels are typically attached tothe framing by any one or more of screws, nails, or glue. Also, in thesystem the exterior sheathing panel typically has no perforations exceptfor perforations made by the screws or nails.

All references cited herein are hereby incorporated by reference to thesame extent as if each reference were individually and specificallyindicated to be incorporated by reference and were set forth in itsentirety herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Unless otherwise specified all percentages, ratios and average molecularweights are on a weight basis.

EXAMPLES Example 1—Gypsum Building Panel

This example illustrates gypsum panel in accordance with the invention.The gypsum panel tested was a ⅝″ (15.875 mm) thick, 48″ (1219 mm)wide×96″ (2438 mm) long, coated glass-mat board. The front and backcover sheets were coated fiber glass face mat and uncoated fiber glassback mat.

This missile impact test was a system test for gypsum board with mesh inthe core and the coverings included foam board adhered to the surface ofthe gypsum board. In this example the test specimen was 20 oz./squareyard (678 grams/square meter) ultra-high impact resistant meshintegrated into GMS (glass mat sheathing) back mat on 1 inch thickexpanded polystyrene (EPS) foam board.

The impact resistant mesh for this example was an Ultra High Impact meshhaving the following properties:

-   -   alkali resistant fiberglass    -   nominal basis areal weight of 20 ounces/yard² (692 g/m²),    -   38 inch (96.5 cm) wide mesh.    -   Ultra high strength Impact Classification of >150 in-lbs        (>17.0 J) according to ASTM E2486 (2018) Standard Test Method        for Impact Resistance of Class PB and PI Exterior Insulation and        Finish Systems (EIFS).

The gypsum panels for the test specimens were prepared for the testingas follows:

The core of the gypsum panel was made from setting an aqueous gypsumslurry mixture and the composition on a dry (water free) basis listed inTABLE 2. The gypsum panel tested had a thickness of about 0.625 inches(15.875 mm).

TABLE 2 Aqueous gypsum slurry composition Ingredients Lbs/MSF Stucco2153.57 Gauging water 1305.43 Foam water 63.58 Soap 0.12 Heat ResistantAccelerator 7.49 Starch 11.02 Dispersant 9.01 Retarder 0.30 Paper fiber9.99 Glass fiber 8.99 Total water 1791.32 Sodium trimetaphosphate at 10%solution in water 6.02 Siloxane 10.99 Fly ash 13.00 Biocide 0.54

The board was made by placing a first non-woven fibrous mat sheet (thatwould become the rear cover sheet) in a mold, then placing the wovenimpact resistant mesh into the mold, and then applying an aqueous gypsumslurry to the non-woven fibrous mat sheet (rear cover sheet) and impactresistant woven scrim mesh in a mold. The gypsum slurry penetrated thenon-woven fibrous mat sheet and embedded the impact resistant wovenscrim mesh. Then a second non-woven fibrous mat sheet (that would becomethe front cover sheet) was applied to the gypsum slurry and the boardwas dewatered and allowed to set. The gypsum slurry embedded the impactresistant woven mesh a distance of about 1/16 to ⅛ inch (1.59 to 3.18mm) from the rear surface of the panel and penetrated into the non-wovenfabric of the front and back cover sheets to bond the non-woven fabricof the front and back cover sheets to the cement panel.

The missile impact test procedures were performed according to the 2017Florida Building Code Test—Protocols for High-Velocity Hurricane Zone,Sixth Edition, Testing Application Standard (TAS) 201-94 Impact TestProcedures.

The test was performed at 73° F., 28% Relative Humidity. The missilelength was 93⅜ inches. The missile mass was 9.01 pounds. The Barrel toSample Distance was 208 feet. Missile speed at impact was 50±1 feet persecond.

The test sample is considered to pass the TAS 201 Missile Impact Test ifthe following two statements are true:

-   -   The missile is rejected (the missile does not penetrate through        the test sample).    -   There is no continuous crack 1/16″ (1.59 mm) wide by 5″ (127 mm)        long (or larger).

Secondarily: If there are no 3/16 inch diameter holes, then the testalso qualifies the product for small missile impact.

TABLE 3 shows the results for testing Sample Board 1 by theabove-described procedure.

TABLE 3 Sample Mis- ID- sile Impact Impact Speed Re- No. Location (fps)Observations sult Sample 1- 42 inches Up 49.9 Test Sample Rejected theMissile. Pass Impact 1 24 inches Right Sample 1- 67 inches Up 50.2Impact Area was on the seam with Pass Impact 2 24 inches 4″ wide meshapplied. Missile was Right rejected. Slight damage to back of sheathingat impact location. Sample 1- 6 inches Up 50.1 Missile punctured throughtest Fail Impact 3 42 inches sample. Right Sample 1- 6 inches Up 50.2N/A no mesh was installed at this N/A Impact 4 6 inches corner. RightSample 1- 42 inches Up 49.8 Foam was cut away from target Fail Impact 542 inches location Prior to test. Missile Right punctured through testsample.

TABLE 4 shows the results for testing Sample Board 2 (having the sameconstruction as Sample Board 1) by the above-described procedure.

TABLE 4 Sample Mis- ID- sile Impact Impact Speed Re- No. Location (fps)Observations sult Sample 2- 42 inches Up 49.3 Test Sample Rejected theMissile. Pass Impact 1 24 inches Right Sample 2- 67 inches Up 50.2 Testlocation was at a seam with no Fail Impact 2 24 inches mesh overlap.Missile punctured Right through the test sample. Sample 2- 29 inches Up49.9 Test location was at a seam Pass Impact 3 24 inches with 6″ wide 15oz/yd2 Right mesh overlap. Test sample rejected the missile. Sample 2-48 inches Up 50.0 Missile rejected. Sheathing cracked Pass Impact 4 6inches but no 1/16″ × 5″ crack noted. The Right sheathing behind theimpact location cracked. Sample 2- 6 inches Up 49.8 Missile passedthrough sheathing. Fail Impact 5 42 inches Right Sample 2- 6 inches UpShims were placed between the Fail Impact 56 6 inches sheathing and theframe in order to Right fill the gap caused by the sheathing restingagainst the head of the stud to plate screw. Missile passed through thesheathing.

FIG. 4 shows a photograph of a front view of Test Sample 1 Impact 1 ofthe examples.

FIG. 5 shows a photograph of a rear view of Test Sample 1 Impact 1 ofthe examples.

FIG. 6 shows a photograph of a front view of Test Sample 1 Impact 2 ofthe examples.

FIG. 7 shows a photograph of a rear view of Test Sample 1 Impact 2 ofthe examples.

FIG. 8 shows a photograph of a front view of Test Sample 1 Impact 3 ofthe examples.

FIG. 9 shows a photograph of a front view of Test Sample 1 Impact 4 ofthe examples.

FIG. 10 shows a photograph of a front view of Test Sample 2 Impact 1 ofthe examples.

FIG. 11 shows a photograph of a front view of Test Sample 2 Impact 2(comparative example, no mesh at joint) of the examples.

FIG. 12 shows a photograph of a front view of Test Sample 2 Impact 3 ofthe examples.

FIG. 13 shows a photograph of a rear view of Test Sample 2 Impact 3 ofthe examples.

FIG. 14 shows a photograph of a front view of Test Sample 2 Impact 4(comparative example) of the examples.

FIG. 15 shows a photograph of a front view of Test Sample 2 Impact 5(comparative example) of the examples.

FIG. 16 shows a photograph of a front view of Test Sample 2 Impact 6(comparative example) of the examples.

FIG. 17 shows a photograph of a rear view of Test Sample 2 Impact 6(comparative example) of the examples.

The data of TABLES 3 and 4 and FIGS. 4-17 shows that the board of theinvention meets the Testing Application Standard (TAS) 201 MissileImpact Test.

Clauses of the Invention

Clause 1. A building panel comprising, from front to back:

-   -   a first fibrous mat,    -   a gypsum core layer having front and rear surfaces, the gypsum        core layer having a thickness of 0.5 to 1.25, preferably 0.5 to        1, inches, wherein the first fibrous mat is attached as a facer        cover sheet to the front surface of the gypsum core layer,    -   an impact resistant woven scrim mesh, embedded ¼ to 1/16 inch,        preferably ⅛ to 1/16 inch, from the rear surface of the gypsum        core layer,    -   a second fibrous mat attached as a backer cover sheet to the        rear surface of the gypsum core layer,    -   wherein the gypsum core layer comprises at least 75 wt. %        calcium sulfate material, wherein the gypsum core layer        comprises less than 10 wt. % magnesium oxide, preferably less        than 5 wt. % magnesium oxide, most preferably an absence of        magnesium oxide;    -   wherein the first fibrous mat and second fibrous mat        respectively comprise paper or fibrous material of at least one        of polymer fibers, glass fibers, mineral fibers or a combination        thereof,    -   wherein the impact resistant mesh has an Impact Range        Classification of >150 in-pounds (>17.0 J) (also known as        “Ultra-High”) according to ASTM E2486 (2018) Standard Test        Method for Impact Resistance of Class PB and PI Exterior        Insulation and Finish Systems (EIFS).

Clause 2. The building panel of Clause 1, wherein the impact resistantmesh has one or more of the following properties:

-   -   fabric surface weight of 20 to 30 ounces per square yard (690 to        1035 g/m²) (measured according to ASTM D3776/D3776M-09a (2017),        Standard Test Methods for Mass Per Unit Area (Weight) of Fabric,        ASTM International, West Conshohocken, Pa., 2017),    -   a thickness of 0.040 to 0.045 inches (1.02 to 1.14 mm)(measured        according to ASTM D-1777-96 (2015), Standard Test Method for        Thickness of Textile Materials, ASTM International, West        Conshohocken, Pa., 2015), and    -   a minimum tensile strength of 350 to 540 pounds-force per inch        (2.41 to 3.72 MPa) in the warp and weft, respectively (measured        according to ASTM D-5035-11 (2019), Standard Test Method for        Breaking Force and Elongation of Textile Fabrics (Strip Method),        ASTM International, West Conshohocken, Pa., 2017).

Clause 3. The building panel of Clause 1 or 3, wherein the exteriorsheathing building panel of the invention provides an exterior sheathingbuilding panel that meets 2017 Florida Building Code Test—Protocols forHigh-Velocity Hurricane Zone, Chapter 16, Section 1626, Sixth Edition,to be capable of resisting a 2 inches×4 inches (51 mm×102 mm) missileweighing 9 pounds (4.1 kg) in accordance with 2017 Florida Building CodeTest—Testing Application Standard (TAS) 201-94 Impact Test Procedures.

Clause 4. The building panel of Clause 3, wherein this missile is a 2inch×4 inch×8 foot wood stud, and the missile shall impact the surfaceof each test specimen at a speed of 50 feet per second (34 miles perhour; 15.2 m/s).

Clause 5. The building panel of any of Clauses 1 to 4, wherein the meshis spaced from the rear mat to form a gap filled with slurry to bond themat to core bond, wherein the gap is about 1/16 inch-⅛ inch embedment.

Clause 6. The building panel of any of Clauses 1 to 5, wherein theslurry penetration into each said mat ranges from 40 to 60% of therespective mat thickness.

Clause 7. The building panel of any of Clauses 1 to 6, wherein thecementitious core comprises a gypsum panel core layer comprisingcementitious material comprising at least 85 weight % calcium sulfatedihydrate, more typically at least 95 weight % calcium sulfatedihydrate.

Clause 8. The building panel of any of Clauses 1 to 7, wherein a firstskim layer is located between the first fibrous mat and the gypsum corelayer.

Clause 9. The building panel of Clause 8, wherein a second skim layer islocated between the second fibrous mat and the gypsum core layer;

Clause 10. The building panel of Clause 1,

-   -   wherein the impact resistant mesh comprises an alkali resistant        fiberglass mesh reinforcement embedded in the core layer, and        wherein the fiberglass mesh reinforcement is a mesh scrim having        about 4×4 to 6×6 strand per inch construction in the        longitudinal and transverse direction, respectively,    -   wherein the fiberglass mesh reinforcement is made from a        fiberglass yarn, the yarn in an uncoated state has a nominal        density of about 1200 to 5000 linear yards per pound of        fiberglass yarn, and    -   wherein the fiberglass yarn comprises 0-65 wt. %, for example        5-65 wt. %, coating on a dry (water free) basis; and    -   wherein the coating comprises alkali resistant polymer.

Clause 11. The building panel of Clause 1, wherein at least one of thefirst and second fibrous mats respectively comprises coated woven saidfiber material or uncoated woven said fiber material.

Clause 12. The building panel of Clause 1, wherein at least one of thefirst and second fibrous mats respectively comprises coated non-wovensaid fiber material or uncoated non-woven said fiber material.

Clause 13. A method of making the building panel of any of Clauses 1 to12, comprising:

-   -   depositing a first fibrous mat as a face mat on a surface,    -   mixing at least water and calcium sulfate material to prepare an        aqueous gypsum slurry comprising at least 75 wt. % calcium        sulfate material on a dry (water free) basis, wherein said        calcium sulfite material comprises calcium sulfate hemihydrate,    -   wherein the aqueous gypsum slurry comprises less than 10 wt. %        magnesium oxide on a dry (water free) basis, preferably less        than 5 wt. % magnesium oxide on a dry (water free) basis, most        preferably an absence of magnesium oxide;    -   applying the aqueous gypsum slurry in a bonding relation to the        face mat to form a gypsum core layer, the gypsum core layer        having a face side and a back side, wherein the gypsum core        layer face side faces said face mat;    -   applying an impact resistant woven scrim mesh on the back side        of the gypsum core layer to embed the impact resistant woven        scrim mesh into the gypsum core layer;    -   applying a second fibrous mat as a back mat on the back side of        the gypsum core layer having the embedded impact resistant mesh        to form a board precursor, thereby locating the aqueous slurry        between the face mat and the back mat;    -   allowing the aqueous gypsum slurry located between the face mat        and the back mat to set, thereby forming the gypsum exterior        sheathing building panel.

Clause 14. The method of Clause 13, wherein the impact resistant mesh isembedded on the top of the deposited slurry such that a portion ofslurry is exposed over the embedded impact resistant mesh, and coveringthe wet slurry with the backer cover sheet of the same type of materialas the facer cover sheet, whereby the cementitious slurry and embeddedimpact resistant mesh is sandwiched between the two cover sheets.

Clause 15. The method of Clause 13, wherein the calcium sulfate materialand water are mixed resulting in the aqueous gypsum slurry having atleast 75 wt. %, preferably at least 85 wt. %, most preferably at least95 wt. %, on a dry basis calcium sulfate hemihydrate, and wherein excesswater is removed from the gypsum slurry by drying and rehydration whichconverts the calcium sulfate hemihydrate to the calcium sulfatedihydrate of a set gypsum core.

Clause 16. The method of Clause 13, wherein the aqueous gypsum slurrycontains 75 to 100 wt. % reactive powder on a dry (water free) basis toprovide the aqueous gypsum slurry with at least 75 wt. % calcium sulfatematerial on a dry (water free) basis, preferably at least 75 wt. %calcium sulfate hemihydrate on a dry (water free) basis.

Clause 17. An exterior sheathing system of a building comprising framingto which is attached a plurality of said exterior sheathing panels ofany of Clauses 1 to 12, wherein the rear mat faces towards the framing,wherein the exterior sheathing panel is on an exterior of the building.

The invention is not to be limited by the above description but ratherby the claims amended hereto.

We claim:
 1. A building panel comprising, from front to back: a firstnonwoven fibrous mat, a continuous gypsum core layer having front andrear surfaces, the gypsum core layer having a thickness of 0.5 to 1.25inches, wherein the first fibrous mat is directly attached as a facercover sheet to the front surface of the gypsum core layer and the gypsumcore layer penetrates into the first fibrous mat, an impact resistantwoven scrim mesh, embedded ¼ to 1/16 inch from the rear surface of thegypsum core layer, a second nonwoven fibrous mat directly attached as abacker cover sheet to the rear surface of the gypsum core layer and thegypsum core layer penetrates into the second fibrous mat, wherein thebuilding panel has only one woven scrim mesh embedded in the gypsum corelayer between the facer and backer cover sheets, wherein the gypsum corelayer comprises at least 75 wt. % calcium sulfate material, wherein thegypsum core layer comprises less than 10 wt.% magnesium oxide; whereinthe first fibrous mat and second fibrous mat respectively comprise paperor fibrous material of at least one of polymer fibers, glass fibers,mineral fibers or a combination thereof, wherein the impact resistantmesh has an Impact Range Classification of >150 in-pounds (>17.0 J)according to ASTM E2486, 2018, Standard Test Method for ImpactResistance of Class PB and PI Exterior Insulation and Finish Systems(EIFS); wherein the impact resistant mesh has the following properties:fabric surface weight of 20 to 30 ounces per square yard (690 to 1035g/m²) as measured according to ASTM D3776/D3776M-09a, 2017, StandardTest Methods for Mass Per Unit Area, Weight of Fabric, and a minimumtensile strength of 350 to 540 pounds-force per inch (2.41 to 3.72 MPa)in the warp and weft, respectively as measured according to ASTMD-5035-11, 2019, Standard Test Method for Breaking Force and Elongationof Textile Fabrics, Strip Method, wherein the building panel of theinvention provides an exterior sheathing building panel that meets 2017Florida Building Code Test—Protocols for High-Velocity Hurricane Zone,Chapter 16, Section 1626, Sixth Edition, to be capable of resisting a 2inches×4 inches (51 mm×102 mm) missile weighing 9 pounds (4.1 kg) inaccordance with 2017 Florida Building Code Test—Testing ApplicationStandard (TAS) 201-94 Impact Test Procedures.
 2. The building panel ofclaim 1, wherein the impact resistant mesh has a thickness of 0.040 to0.045 inches as measured according to ASTM D-1777-96, 2015, StandardTest Method for Thickness of Textile Materials.
 3. The building panel ofclaim 1, wherein the mesh is spaced from the second fibrous mat to forma gap filled with slurry to bond the second fibrous mat to the corelayer, wherein the qap is about 1/16 inch-⅛ inch embedment, wherein thegypsum core layer is formed from a slurry, wherein the slurrypenetration into each said mat ranges from 40 to 60% of the respectivemat thickness, wherein the impact resistant mesh comprises an alkaliresistant fiberglass mesh reinforcement embedded in the core layer, andwherein the fiberglass mesh reinforcement is a mesh scrim having about4×4 to 6×6 strand per inch construction in the longitudinal andtransverse direction, respectively, wherein the fiberglass meshreinforcement is made from a fiberglass yarn, the yarn in an uncoatedstate has a nominal density of about 1200 to 5000 linear yards per poundof fiberglass yarn, wherein the cementitious core comprises a gypsumpanel core layer comprising cementitious material comprising at least 85weight % calcium sulfate dihydrate, and wherein the fiberglass yarncomprises 0-65 wt. % coating on a dry basis; and wherein the coatingcomprises alkali resistant polymer, wherein the first fibrous mat andsecond fibrous mat respectively comprise glass fibers, wherein thismissile is a 2 inch×4 inch×8 foot wood stud, and the missile shallimpact the surface of each test specimen at a speed of 50 feet persecond (34 miles per hour; 15.2 m/s).
 4. The building panel of claim 1,wherein this missile is a 2 inch×4 inch×8 foot wood stud, and themissile shall impact the surface of each test specimen at a speed of 50feet per second (34 miles per hour; 15.2 m/s).
 5. The building panel ofclaim 1, wherein the mesh is spaced from the second fibrous mat to forma gap filled with slurry to bond the second fibrous mat to the corelayer, wherein the gap is about 1/16 inch-⅛ inch embedment.
 6. Thebuilding panel of claim 1, wherein the gypsum core layer is formed froma slurry, wherein the slurry penetration into each said mat ranges from40 to 60% of the respective mat thickness.
 7. The building panel ofclaim 1, wherein the cementitious core comprises a gypsum panel corelayer comprising cementitious material comprising at least 85 weight %calcium sulfate dihydrate.
 8. The building panel of any of claim 1,wherein a first skim layer is located between the first fibrous mat andthe gypsum core layer.
 9. The building panel of claim 8, wherein asecond skim layer is located between the second fibrous mat and thegypsum core layer.
 10. The building panel of claim 1, wherein the impactresistant mesh comprises an alkali resistant fiberglass meshreinforcement embedded in the core layer, and wherein the fiberglassmesh reinforcement is a mesh scrim having about 4×4 to 6×6 strand perinch construction in the longitudinal and transverse direction,respectively, wherein the fiberglass mesh reinforcement is made from afiberglass yarn, the yarn in an uncoated state has a nominal density ofabout 1200 to 5000 linear yards per pound of fiberglass yarn, andwherein the fiberglass yarn comprises 0-65 wt. % coating on a dry basis;and wherein the coating comprises alkali resistant polymer.
 11. Thebuilding panel of claim 1, wherein at least one of the first and secondfibrous mats comprises coated non-woven said fiber material.
 12. Thebuilding panel of claim 1, wherein at least one of the first and secondfibrous mats comprises uncoated non-woven said fiber material.
 13. Anexterior sheathing system of a building comprising framing to which isattached a plurality of said building panels of claim 1, wherein therear mat faces towards the framing, wherein the panel is on an exteriorof the building.
 14. The building panel of claim 1, wherein the firstfibrous mat and second fibrous mat respectively comprise at least one ofpolymer fibers, glass fibers, mineral fibers or a combination thereof.15. The building panel of claim 1, wherein the first fibrous mat andsecond fibrous mat respectively comprise glass fibers.
 16. The buildingpanel of claim 4, wherein the first fibrous mat comprises a coated fiberglass mat and the second fibrous mat comprises an uncoated fiber glassmat.
 17. A method of making the building panel of claim 1, comprising:depositing a first fibrous mat as a face mat on a surface, mixing atleast water and calcium sulfate material to prepare an aqueous gypsumslurry comprising at least 75 wt. % calcium sulfate material on a dry(water free) basis, wherein said calcium sulfite material comprisescalcium sulfate hemihydrate, wherein the aqueous gypsum slurry comprisesless than 10 wt. % magnesium oxide on a dry (water free) basis; applyingthe aqueous gypsum slurry in a bonding relation to the face mat to forma gypsum core layer, the gypsum core layer having a face side and a backside, wherein the gypsum core layer face side faces said face mat;applying an impact resistant woven scrim mesh on the back side of thegypsum core layer to embed the impact resistant woven scrim mesh intothe gypsum core layer; applying a second fibrous mat as a back mat onthe back side of the gypsum core layer having the embedded impactresistant mesh to form a board precursor, thereby locating the aqueousslurry between the face mat and the back mat; allowing the aqueousgypsum slurry located between the face mat and the back mat to set,thereby forming the gypsum exterior sheathing building panel.
 18. Themethod of claim 17, wherein the impact resistant mesh is embedded on thetop of the deposited slurry such that a portion of slurry is exposedover the embedded impact resistant mesh, and covering the wet slurrywith the backer cover sheet of the same type of material as the facercover sheet, whereby the cementitious slurry and embedded impactresistant mesh is sandwiched between the two cover sheets.
 19. Themethod of claim 17, wherein the calcium sulfate material and water aremixed resulting in the aqueous gypsum slurry having at least 75 wt. % ona dry basis calcium sulfate hem ihydrate, and wherein excess water isremoved from the gypsum slurry by drying and rehydration which convertsthe calcium sulfate hem ihydrate to the calcium sulfate dihydrate of aset gypsum core.
 20. The method of claim 17, wherein the aqueous gypsumslurry contains 75 to 100 wt. % reactive powder on a dry (water free)basis to provide the aqueous gypsum slurry with at least 75 wt. %calcium sulfate material on a dry (water free) basis.